Moisture monitoring system
First Claim
1. A sensor for measuring moisture in a medium, comprising:
- a first conductive plate disposed in a plane, said first plate having a first terminal;
a second conductive plate coplanar with said first conductive plate and not in contact with said first conductive plate, said second plate having a second terminal;
a casing made of a dielectric material, said first and second plates embedded in said casing with said terminals protruding from said casing, said casing having a thickness in a dimension normal to said plane; and
said thickness varies across said plane.
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Accused Products
Abstract
A capacitive moisture sensor has two conductors encased in a dielectric material and oriented to minimize the dielectric effect of the moisture-absorbent medium in which the sensor is placed. The conductors, the casing, or both have one or more physical dimensions that vary monotonically across the length of the sensor. The physical dimensions vary in a manner that produces a linear relationship between moisture level and sensor impedance. The physical dimension may be the thickness of the dielectric casing or the spacing between portions of the conductors. In another aspect, the present invention has an irrigation control system with a central control unit and multiple remote units. Each remote unit has a moisture sensor and transmits a measured moisture level to the central control unit. In response to the measured moisture level, the central control unit determines whether to open or close a valve controlling the irrigation of the area in which the sensor is located.
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Citations
44 Claims
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1. A sensor for measuring moisture in a medium, comprising:
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a first conductive plate disposed in a plane, said first plate having a first terminal; a second conductive plate coplanar with said first conductive plate and not in contact with said first conductive plate, said second plate having a second terminal; a casing made of a dielectric material, said first and second plates embedded in said casing with said terminals protruding from said casing, said casing having a thickness in a dimension normal to said plane; and said thickness varies across said plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A sensor for measuring moisture in a medium, comprising:
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a first conductor having a first terminal and a plurality of parallel conductive teeth disposed in a plane; a second conductor not in contact with said first conductor, said second conductor having a second terminal and a plurality of parallel conductive teeth coplanar with said teeth of said first conductor and interleaved with said teeth of said first conductor, each said tooth being separated from an adjacent one of said teeth by a spacing; a casing made of a dielectric material, said conductors embedded in said casing with said terminals protruding from said casing, said casing having a thickness in a dimension normal to said plane; and said spacing between adjacent teeth varies across said plane. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A sensor for measuring moisture in a medium, comprising:
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a first conductor having a first terminal and a plurality of parallel conductive teeth disposed in a plane, spacing between adjacent teeth varying across said plane; a second conductor not in contact with said first conductor; and a casing made of a dielectric material, said conductors embedded in said casing with said terminals protruding from said casing, said casing having a thickness in a dimension normal to said plane. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A moisture monitoring system, comprising:
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a central unit for communicating with at least one remote unit, comprising; power supply means for providing a power signal; first detector means for extracting a moisture measurement signal imposed on said power signal; processor means for receiving said moisture measurement signal; and at least one remote unit disposed at a location remote from said central unit and receiving power from said power signal, comprising; a sensor for measuring a moisture level in a medium and for producing a moisture measurement signal corresponding to said measured moisture level; and remote unit modulator means for imposing said moisture measurement signal on said power signal. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A moisture control system, comprising:
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a central unit for controlling at least one valve, comprising; power supply means for providing a power signal; central unit detector means for extracting a moisture measurement signal imposed on said power signal; processor means for receiving said moisture measurement signal and for producing a valve control signal; and central unit modulator means for imposing said valve control signal on said power signal; at least one remote unit disposed at a location remote from said central unit and receiving power from said power signal, comprising; a sensor for measuring a moisture level in a medium and for producing a moisture measurement signal corresponding to said measured moisture level; and remote unit modulator means for imposing said moisture measurement signal on said power signal; remote unit detector means for extracting said valve control signal imposed on said power signal; and a valve controller for controlling water flow in response to said valve control signal. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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Specification